Cummins 4BT & Diesel Conversions Forums banner

4BT MPG Challenge

107K views 28 replies 22 participants last post by  chevy43 
#1 · (Edited)
When I originally started my 4BT project, I read where everyone was getting 28+ MPG out of Jeep Wranglers with 33" tires. So, I bought a Jeep Wrangler and started my build. Later, I realized it seemed nobody had any hard evidence supporting their claims. The posts always read something like 'I was on this one trip, it lasted for this many miles and I used about this much fuel.' Or there's a post where someone posts their average and you're expected to believe it. The point still is there's no real data to support the claim.

So, here's the chance to put up or shut up about your mileage guys. Starting today, I'm offering a challenge to you to see what your 'real' numbers are. All you you need to do is make ONE post. Put in it - your vehicle specs, the area you drive, and most important your fuel record.

Once you've done that, all you need to do is edit that one post with new information build your record with actual starting ending mileages and purchases. We're talking raw data. Not just the total average number. I'll start with mine on the next post so you can see what I'm looking for. Your welcome to use it as a template.
 
#2 · (Edited)
1994 Jeep Wrangler

Area of Operation:
United States, South Eastern Indiana

Current Configuration:
Engine: Cummins 4BT Stock Turbo
Transmission: General Motors TH-400 3-Speed Auto
Transfer Case: New Process 231
Rear Unit: Ford 8.8 (2.73)
Front unit: Jeep Dana 44 (2.73)
Tires: Mickey Thompson Baja Claw (33x15.5x15)

Fuel Record:

2007
P. Date - Odometer - Qty - Price - MPG
10/20/07 - 000,000 - 17.00 - 0.NA - 19.5
11/15/07 - 000,331 - 10.00 - 3.50 - 17.2
11/19/07 - 000,503 - 05.70 - 3.50 - 16.3
11/20/07 - 000,596 - 14.29 - 3.50 - 18.2
11/26/07 - 000,856 - 18.30 - 3.54 - 18.1
12/12/07 - 001,187 - 19.70 - 3.30 - 15.0
12/24/07 - 001,483 - 18.10 - 3.33 - 16.4
Annual MPG - 17.24​

2008
P. Date - Odometer - Qty - Price - MPG
01/16/08 - 001,779 - 18.52 - 3.35 - 16.4
01/29/08 - 002,083 - 19.10 - 3.30 - 14.2
02/20/08 - 002,355 - 16.77 - 3.58 - 17.8
03/05/08 - 002,653 - 07.90 - 3.78 - 20.2
03/21/08 - 002,813 - 19.50 - 4.16 - 14.8
04/03/08 - 003,101 - 19.47 - 4.06 - 16.0
05/24/08 - 003,690 - 18.90 - 4.83 - 18.6
06/25/08 - 004,041 - 19.35 - 4.86 - 19.3
07/07/08 - 004,414 - 19.55 - 4.86 - 18.6
07/28/08 - 004,778 - 20.22 - 4.70 - 19.5
08/20/08 - 005,172 - 19.55 - 4.59 - 18.8
09/17/08 - 005,547 - 19.96 - 4.16 - 17.7
Estimate - 005,925 - 20.50 - 4.05 - 18.6
11/01/08 - 006,307 - 19.75 - 3.09 - 17.6
11/25/08 - 006,655 - 20.80 - 2.69 - 14.9​
Annual MPG = 17.53

2009
P. Date - Odometer - Qty - Price - MPG
Estimate - 006,965 - 20.50 - 2.16 - 15.0
02/24/09 - 007,272 - 19.46 - 2.16 - 17.8
03/16/09 - 007,619 - 20.01 - 2.00 - 17.2
03/24/09 - 007,963 - 19.19 - 2.19 - 17.7
04/06/09 - 008,303 - 20.00 - 2.20 - 18.5
04/19/09 - 008,672 - 20.01 - 2.26 - 17.2
05/22/09 - 009,017 - 19.33 - 2.33 - 17.1
06/22/09 - 009,347 - 20.75 - 2.70 - 17.2
07/12/09 - 009,703 - 20.31 - 2.66 - 17.4
08/16/09 - 010,057 - 20.01 - 2.70 - 17.9
09/09/09 - 010,416 - 20.01 - 2.70 - 18.0
09/30/09 - 010,776 - 20.92 - 2.60 - Soon
Annual MPG = 17.36​

Overall MPG: 17.38
 
#3 ·
I don't have my 4BT in a donor yet, but I have a 3/4 4x4 Dodge Cummins with a p-pumped 12V and I get 2 more mpg by adding a quart of two stroke oil and half a bottle of Power Service to each fill up. I do this to help lubricate the injection pump (I don't truct USLD). The extra MPG is a bonus. I'm averaging 19 mpgs with 4:10 gears.
 
#5 ·
I once got 25MPG in my J300 (4BT/NV4500/NP200/3.08), but I typically get 23MPG. Not spectacular, but considering that it doubled the MPG from the gas engine...
 
#6 ·
I can attain 27 mpg fairly regularly in mine. Stock engine and turbo with pump turned up some. Running an intercooler. Traveling 65-70 in somewhat hilly terrain. I was tracking my speed an distance with a handheld GPS and just topped one of my tanks up to the brim. I have beat this number one time and made it into the 30 mark. This was with a 50 mph tailwind and an elevation drop of about 3000 feet over the course of 135 miles. 25 mpg is always possible around town.

This is in my K10 short box with 33x12.50x16.5 BFG all-terrains. 3.73 gears. NV4500. I have no idea what it weighs. Some sheetmetal bobbed to remove rust but also running 14 bolt semi floater rear end.

I am now tuning in a new turbo set-up. I hope it doesn't go down, but it seems doubtful that it will go up.
 
#7 · (Edited)
1977 Ford Bronco 4bt

I will play the game as soon as I get the rear driveshaft back in.....I plan to drive several hundred miles this weekend.

Area of Operation:
United States, South Carolina

Current Configuration:
Engine: Cummins 4BT Turbo
Engine changes: K&N Air Filter, Fuel Pump Timing Advanced 2+ degrees, H1C turbo w/16cm turbine housing
Truck: 1977 Ford Bronco with dual Tanks
Transmission: Ford C4 3-Speed Auto, Art Carr Manual Reverse Shift Valve Body, additional capacity sump
Transfer Case: Dana 20
Rear Unit: Ford 9" (3.5)
Front unit: Dana 44 (3.5)
Tires: BFG KM2 (35x12.5x17)

Current hard acceleration measurements from 45mph to 70mph
Max boost = 16psi
Max EGT = 900 Deg F
RPM at 70mph = 2,350

Fuel: ULSD

Fuel Record:

2009
P. Date - Odometer(Miles) - Qty(gal) - Price($) - MPG
08/22/09 000,079 Filled up $2.49 N/Available
08/22/09 000,180 5.12 $2.49 19.73 Mostly 70mph
09/05/09 000,419 12.18 $2.49 19.62 City driving
09/07/09 000,743 14.81 $2.49 21.88 Mostly 55-60 mph
11/6/09 001,090 18.09 $2.65 19.18 Mostly to & from work 7 miles each way

Total Average = 20.14 mpg
 
#8 · (Edited)
63 Chevy extended cab

AREA OF OPERATION
Colorado,Utah,New Mexico
4000 - 10000ft elavation

Current Configuration
Cummins 4Bt CPL 0593, 1.85mm plunger depth, 6BT H1C turbo
Transmission: SM420 with Ranger overdrive (27%)
Tcase: Rockwell T221
Front axle Corp. 10 bolt
Rear axle Corp. 14 bolt (4.10 gear)
Tires: Uniroyal Liberators 285/75/16, 50psi
Weight: 6085 lbs

FUEL RECORD

3.42 Gears

1/25/06 28202.4
2/15/06 28717.1 22gal 23.4mpg
3/7/06 28978.8 10gal 23.87mpg
3/19/06 29380.0 18.1gal 22.17
29706.7 15.67gal 20.85mpg
4/17/06 29955.3 9.8gal 25.4mpg
4/18/06 30305.7 9.06gal 19.5mpg
4/19/06 30513.8 9.05gal 22.97mpg
4/19/06 30720.7 9.5gal 21.78mpg
4/19/06 31117.0 18.4gal 21.5mpg
4/20/06 31477.9 19.3gal 18.69mpg
4/20/06 31783.5 17.4gal 17.56mpg
4/20/06 31932.0 9.13gal 16.27mpg
4/20/06 32098.0 8.40gal 19.76mpg
4/21/06 32625.7 23.6gal 22.4mpg
5/14/06 32939.3 12.07gal 25.98mpg
5/25/06 33243.8 11.45gal 26.59mpg
6/07/06 33418.9 8.27gal 21.17mpg
6/29/06 33998.2 22.7gal 25.5mpg
7/20/06 34257.2 11.7gal 22.13mpg
8/06/06 34600.0 15.66gal 21.9mpg
8/19/06 34846.0 10.86gal 22.7mpg
9/27/06 35291.6 20gal 22.3mpg
35359.9 3.9gal 17.5mpg
4.10 GEARS
10/21/06 35665.3 13.2gal 23.7mpg
11/11/06 36029.0 17.0gal 21.4mpg
01/11/07 36610.1 27.7gal 21 mpg
01/25/07 36776.7 7.8gal 21.3mpg
01/26/07 36988.8 14 gal 15.2mpg
03/06/07 37327.6 16 gal 21.2mpg
04/01/07 37729.3 16.2gal 24.9mpg
05/01/07 38136.2 15.97 25.5
05/22/07 38454.0 13.44 23.7
05/30/07 38897.9 16.6 26.7
06/17/07 39474.4 24.2 23.8
06/26/07 39746.4 9.64gal 28.2mpg
07/10/07 40182.6 19.2 22.7
07/25/07 40459.7 11.7 23.7
08/02/07 40657.1 8.3 23.78
08/13/07 41239.2 22.2gal 26.22mpg
08/16/07 41548.1 10.3 30 mpg
09/04/07 41905.2 14.8gal 24.2mpg
10/03/07 42294.0 15.97 24.35
10/30/07 42816.6 21 24.88
11/21/07 43140.0 13.6gal 23.74mpg
11/30/07 43553.7 17.4 23.78
12/07/07 43890.4 14.5 23.19
12/16/07 44273.0 16.5 23.19
02/24/08 44669.9 18.9gal 21 mpg
03/15/08 44759.1 16.04
07/01/08 45941.5
07/15/08 46364.2 15.5gal 27.2mpg
07/23/08 46701.6 13.18gal 25.59mpg
07/27/08 47043.3 12.8 26.7mpg
09/15/08 47426.0 11.0gal 23.9
11/07/08 47958.5 22.7 23.5mpg
12/15/08 48396.9 18.06 24.3
01/25/09 48835.5 22.5gal 19.5mpg
02/12/09 49219.3 15.5 24.76
02/20/09 49495.3 10.95 25.2
02/25/09 49952.4 19.7gal 23.2mpg
05/04/09 50472.3 20 gal 25.98mpg
07/17/09 50762.1 12.2 23.8
07/24/09 51184.2 15.9gal 26.5mpg

Average 23.1
 
#9 ·
What gearing did you have for the first data set?


AREA OF OPERATION
Colorado,Utah,New Mexico
4000 - 10000ft elavation

Current Configuration
Cummins 4Bt CPL 0593, 1.85mm plunger depth, 6BT H1C turbo
Transmission: SM420 with Ranger overdrive (27%)
Tcase: Rockwell T221
Front axle Corp. 10 bolt
Rear axle Corp. 14 bolt (4.10 gear)
Tires: Uniroyal Liberators 285/75/16, 50psi
Weight: 6085 lbs

FUEL RECORD

1/25/06 28202.4
2/15/06 28717.1 22gal 23.4mpg
3/7/06 28978.8 10gal 23.87mpg
3/19/06 29380.0 18.1gal 22.17
29706.7 15.67gal 20.85mpg
4/17/06 29955.3 9.8gal 25.4mpg
4/18/06 30305.7 9.06gal 19.5mpg
4/19/06 30513.8 9.05gal 22.97mpg
4/19/06 30720.7 9.5gal 21.78mpg
4/19/06 31117.0 18.4gal 21.5mpg
4/20/06 31477.9 19.3gal 18.69mpg
4/20/06 31783.5 17.4gal 17.56mpg
4/20/06 31932.0 9.13gal 16.27mpg
4/20/06 32098.0 8.40gal 19.76mpg
4/21/06 32625.7 23.6gal 22.4mpg
5/14/06 32939.3 12.07gal 25.98mpg
5/25/06 33243.8 11.45gal 26.59mpg
6/07/06 33418.9 8.27gal 21.17mpg
6/29/06 33998.2 22.7gal 25.5mpg
7/20/06 34257.2 11.7gal 22.13mpg
8/06/06 34600.0 15.66gal 21.9mpg
8/19/06 34846.0 10.86gal 22.7mpg
9/27/06 35291.6 20gal 22.3mpg
35359.9 3.9gal 17.5mpg
4.10 GEARS
10/21/06 35665.3 13.2gal 23.7mpg
11/11/06 36029.0 17.0gal 21.4mpg
01/11/07 36610.1 27.7gal 21 mpg
01/25/07 36776.7 7.8gal 21.3mpg
01/26/07 36988.8 14 gal 15.2mpg
03/06/07 37327.6 16 gal 21.2mpg
04/01/07 37729.3 16.2gal 24.9mpg
05/01/07 38136.2 15.97 25.5
05/22/07 38454.0 13.44 23.7
05/30/07 38897.9 16.6 26.7
06/17/07 39474.4 24.2 23.8
06/26/07 39746.4 9.64gal 28.2mpg
07/10/07 40182.6 19.2 22.7
07/25/07 40459.7 11.7 23.7
08/02/07 40657.1 8.3 23.78
08/13/07 41239.2 22.2gal 26.22mpg
08/16/07 41548.1 10.3 30 mpg
09/04/07 41905.2 14.8gal 24.2mpg
10/03/07 42294.0 15.97 24.35
10/30/07 42816.6 21 24.88
11/21/07 43140.0 13.6gal 23.74mpg
11/30/07 43553.7 17.4 23.78
12/07/07 43890.4 14.5 23.19
12/16/07 44273.0 16.5 23.19
02/24/08 44669.9 18.9gal 21 mpg
03/15/08 44759.1 16.04
07/01/08 45941.5
07/15/08 46364.2 15.5gal 27.2mpg
07/23/08 46701.6 13.18gal 25.59mpg
07/27/08 47043.3 12.8 26.7mpg
09/15/08 47426.0 11.0gal 23.9
11/07/08 47958.5 22.7 23.5mpg
12/15/08 48396.9 18.06 24.3
01/25/09 48835.5 22.5gal 19.5mpg
02/12/09 49219.3 15.5 24.76
02/20/09 49495.3 10.95 25.2
02/25/09 49952.4 19.7gal 23.2mpg
05/04/09 50472.3 20 gal 25.98mpg
07/17/09 50762.1 12.2 23.8
07/24/09 51184.2 15.9gal 26.5mpg
 
#10 ·
63 Chevy extended cab

I had 3.42 gears in it, worked good on the highway but sucked around town and in the moutains.
 
#12 · (Edited)
Here's this years list.
3.73 gears/NV4500/BFG 33/10.50/15 MUD's

In town driving except where noted.

Jan 12, 09/ 24 mpg
Feb 9, 09/ 21.6 mpg
Feb 20, 09/25.94 mpg
Feb 26, 09/ 21.11 mph Snow run, trip to Crown King and back to Mesa.
Mar 13, 09/ 22.12 mpg
Mar 23, 09/ 21.65 mpg
April 4, 09/ 23.62 mpg
April 24, 09/22.6 mpg
june 15, 09/ 24.14 mpg
June 18, 09/ 19.93 mpg
June 6, 09/ 21.66 mpg
July 14, 09/ 18.91 mpg
July 29, 09/21.94 mpg
Aug 12, 09/20.04 mpg
 
#13 ·
#15 ·
This is a great thread...

In my 1971 Toyota Land Cruiser:

1991 120hp 4BTA, mildly turned up.
WH1C 12cm2 housing Turbo, stock otherwise
NV4500 Dodge Standard Duty (5.6 1st, .27 OD)
NP241
4.10 axle gearing
35" tires
spring over axle lift of approx 5"
aerodynamics of a brick

25mpg regularly attainable highway with all terrain tires.
With Mud terrains and cruising speed of about 2200 rpms, about 22-23 on average.
 

Attachments

#16 ·
its been hard to get mpg lately because my oddometer keeps reseting itself not sure why. i took a trip this last weekend
truck setup
dodge dakota 2003 quad cab 4x4 with front dif temperarily removed
engine: stock 4bt with free pump mods
3.52 stock dif
30 inch bf bfg all terrains

last tank all highway
719.4km- 447miles
58.075L-15.342us gallons
.979$/Liter 57$ for the tank[bc prices are high compared to here at home]
12.387kmperL_ or 29.136 miles per gallon
this is through mountains cruising at 110km/h or 68 miles per hour
on average around town i get around 26-27
and less in winter because of excess slipping[lol] and winter fuel
ps[i accidently put the thumbs down in there ignore that]
 
#19 ·
My last tank of all in town driving. I got 440km's to 59lts at 82cents per litre. I think that equates out to 17 mpg. My in town mileage didn't change much after I did injectors. Haven't gone on a good highway cruise yet with the new injectors. The best tank when the truck was stock was all highway, 550km's to 50lts. I think that's 26mpg?

Stephen
 
#21 ·
I have a 1998 dodge durango 32x10.50 all terrain, 3.55 rear gears. WH1c turbo with 12cm2 housing, 4in exhaust, TH700R4 trans, No intercooler, upgraded fuel pump with torque pin, 3200 gov spring and adjusted starwheel. I drive hard stoplight city to and from work everyday and get 22.2mpg consistantly. The last trip was through the mountians of NC and Tenn. and averaged 25.3 mpg. This was a 380 mile trip from Greenville, SC to Knoxville, Tn back to Greenville and ran 70 most of the way
 
#22 ·
I apologize for the formatting ahead of time...I can email the spreadsheet to someone if the want it. just PM me.

I tried to keep a log for quite a while with my Durango. Below you can see some specifics of the data. I did a mix of driving with the durango including some towing and i tried to seperate it out the best i could. below the main data set i broke it down a bit to look at what the averages were.

edit: oh yea, specs on the Durango. 4bt/nv4500/31's/3.55's/2wd. and i no longer own it...

Fuel Spreadsheet

Date Volume Price Miles MPG Price/mile Note
12/8/2007 6.251 3.359 172 27.5155975 0.122076215
1/1/2008 22.3 3.499 519.4 23.29147982 0.150226608
1/1/2008 22.3 3.499 519.4 23.29147982 0.150226608
1/9/2008 22.74 3.499 516 22.69129288 0.154200116
1/9/2008 22.74 3.499 516 22.68730215 0.15422724
1/13/2008 9.288 3.359 238.5 25.67829457 0.130810868
1/13/2008 9.288 3.359 238.5 25.67829457 0.130810868
1/21/2008 14.449 3.279 325 22.49290608 0.145779295
1/21/2008 14.449 3.279 325 22.49290608 0.145779295
1/25/2008 13.565 3.239 332 24.4747512 0.132340467
1/25/2008 13.55 3.239 332 24.50184502 0.132194127 estimated see receipt
2/1/2008 23.342 3.459 531.6 22.77439808 0.151881072
3/21/2008 17.339 3.99 437.7 25.24367034 0.158059424
3/23/2008 10.947 4.159 126 11.51000274 0.361337881 towing
4/11/2008 8.954 4.099 147 16.41724369 0.249676503 Towing
5/6/2008 14.207 4.799 377.5 26.57140846 0.180607664
5/9/2008 12.977 4.399 313 24.11959621 0.182382821
5/13/2008 13.231 4.459 350.9 26.52104905 0.168130604
5/17/2008 14.451 4.499 408.6 28.27485987 0.159116615
5/19/2008 10.271 4.599 155 15.09103301 0.30475051 towing
6/13/2008 9.522 4.899 195.3 20.51039698 0.23885447 towing
6/20/2008 13.952 4.799 381.9 27.37241972 0.175322461
7/2/2008 21.457 4.639 466.7 21.7504777 0.213282672
7/12/2008 19.713 4.699 480.7 24.38492365 0.192701034 some towing
7/18/2008 17.788 4.799 417.4 23.46525748 0.204515122
4/6/2009 18.316 2.199 473.5 25.85171435 0.085062057 Intercooler Installed winter '09
4/11/2009 16.36 2.259 404.5 24.72493888 0.091365241 some towing
4/16/2009 17.444 2.259 472.9 27.10960789 0.083328391
4/22/2009 14.79 2.259 403.5 27.28194726 0.082802007
4/28/2009 18.3 2.259 511 27.92349727 0.080899609
4/30/2009 7.031 2.259 176.1 25.04622387 0.090193237

Gallons Price Miles
Overall 471.316 3.641935484 11264.6
No Towing 395.549 9756.1



AVG Including Towing 23.90031317
AVG No Towing 24.66470652
AVG No Towing Since Intercooler 27.16060106
 
#23 ·
I hear what you are saying! I built a 2002 Dodge Ram 1500 Crew Cab, I put a Ford ZF5 5speed in the truck. My gear front and rear are 355., I put 35 Kumo M/T or 315 x 12 I added a air to air and advance the timing. I turned the Star ring all the way down ( Not sure of the name but under the smoke screw that I did not mess with) I turned the fuel pin so the slop was facing to the front.I turned the fuel screw in 3 full turns. Once I have my drive line in I will be happy to give you some info on the fuel MPG. Before I made the changes to the timing I drive it over 100 mile and used 1/8 of a tank of fuel. But I went the next day to dodge and they calibrated the speed odometer for the size of tires I have on it. I topped the truck off and hooked it to my 20ft x 8ft jon boat with 36 gal fuel tank and 115 hp johnson. I pulled it up and down hills both ways and I used not even 1/4 of fuel on 120 miles I will be able to give you the fuel milage once I top it off. I am going to say around 18 or 19 mpg pulling a heavy ass boat. I am like you I need to see the proof before I belive it. It is doing about the same as my 2500 Ram with 6bt 24V . Will update soon
 
#24 ·
We just returned from a trip from Bakersfield CA. to Flagstaff AZ. and back a trip of ~1000 miles towing our trailer so a total weight of 12,000 lbs the truck ran flawlessly other that coolant temps of 210* pulling some of the long grades in the heat of the day,but it cooled down quickly when the road leveled out. We got 14 mpg with an average speed for the whole trip 63 mph and on the way there from Needles CA. @ 500' to Flagstaff @ 7000' ~200 miles the 4BT was running wide open the whole way making 26psi boost with 1200* EGT's this thing likes to work hard ;) Does 14mpg sound like reasonable mileage running that hard? This is the first cross country trip we have taken since the swap and I'm happy with how it went just wondering if that was a good mileage number I "think" it is for as hard as we were pushing it........but I have nothing to compare with.
 
#25 ·
Did you run out of :beer: in Needles? We run about 400 miles and drive ours like we stole it. Same weight around 12 k but tad better on mpg's. If we keep it under 70 it has done about 18. It has a consistent 18 mpg lately used to vary 16-21 but think it has found its sweet spot. Yes poor thing gets flogged but it loves it.l
 
#26 · (Edited)
17.7
Highway or around town, it doesn't care.
37" tires 4.10 gears
1450rpm @55 mph
1850rpm @ 70mph
 
#27 ·
With 37" tires, 3.73 gears and a NV4500, I was getting 20-22 unloaded.

With 35" tires and the above setup I'm getting about 18mpg.
 
#28 ·
92 Ford f150 4x4,m5od with 3.08 rear and front. Stock (235/75 15) tires. Engine is stock except for fuel pin turned 90 degrees and Dodge CAC. Its been a daily driver for 2 1/2 years & 25k+ miles. I calculate MPG every top off as I use the trip meter for a fuel gauge. I have never got less than 22 nor better than 25 mpg no matter how I drive. 65 mph = 1950 rpm per tiny tach.
 
#29 ·
I drive an IH Scout with 6BT,
Ranger overdrive,
SM420,
Dana300,
2.72 gears
31 inch tires.
Area of operation Central Cal.

Years of milage records. Average 24 MPG mixed driving with speeds on the highway around 70MPH.
Best MPG 30 driving from Seattle to central CA at exactly 55 mph with only a couple of stops.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top